92 
IOWA ACADEMY OF SCIENCES. 
being to determine, if possible, the source of the epidemic. 
It was recognized after an investigation of the hygienic 
conditions that the water or milk supply must have been 
the means of transmitting the germ which caused the epi- 
demic. A thorough investigation of the water supply 
proved that there was no indication whatever of any con- 
tamination; and, naturally, attention was given to the 
milk supply as the probable cause of the disease. 
A chemical examination was made of every well which 
supplied water to those who furnished the milk supply. 
All of the samples collected were analyzed at once on 
reaching the laboratory. The results of the analysis 
showed that all of the wells furnished good water except 
one shallow well, which gave the following results: 
Free Ammonia 054 parts per million. 
Albuminoid Ammonia 174 “ “ “ 
Solids on Evaporation .904. “ “ ‘‘ 
Solids at 180° 752. “ “ “ 
Solids on Ignition 440. “ “ “ 
Nitrogen as Nitrites 2 “ “ “ 
Nitrogen as Nitrates 24. “ “ “ 
Oxygen consumed in 15 minutes. . .16 “ “ “ 
Oxygen consumed in 4 hours 96 “ “ 
Chlorine as Chlorides 24. “ “ “ 
When the results of this analysis are examined it will be 
noticed that the amount of nitrogen as nitrates is 24 times 
that of the standard of the State Board of health. The 
large amount of chlorine and solids in addition to the 
large amount of nitrogen as nitrates shows most conclu- 
sively that the well was contaminated. 
A second analysis of water from the same well a short 
time after the first analysis gave the following results: 
Free Ammonia 
.104 paits 
per 
million 
Albuminoid Ammonia 
.086 “ 
a 
“ 
Solids on Evaporation 
8 74. 
* « 
«( 
Solids at 180° 
.714. 
i • 
Solids on Ignition 
,50 6. “ 
< < 
Nitrogen as Nitrates 
. 40. 
(( 
« « 
Nitrogen as Nitrites 
. .16 
<< 
Oxygen consumed in 15 minutes 
. .64 
4 4 
« t 
Oxgen consumed in 4 hours .... 
. .06 
i i 
“ 
Chlorine as Chlorides 
. 26. 
i i 
t ( 
